leetcode 1380. Lucky Numbers in a Matrix

class Solution:
    def luckyNumbers (self, matrix: List[List[int]]) -> List[int]:
        rowMin = []
        colMax=[]
        ans=[]
        for i in matrix:
            rowMin.append(min(i))
        for j in range(len(matrix[0])):
            tmpCol=[]
            for i in range(len(matrix)):
                tmpCol.append(matrix[i][j])
            colMax.append(max(tmpCol))
        for i in rowMin:
            if i in colMax: ans.append(i)
        return ans